The present invention relates to a motor-operated machine, especially a portable electric tool, with a means of varying the torque, with a torque-disengagement mechanism, an operating spindle, and a driveshaft with at least one interposed pair of wheels, preferably cogwheels. The function of the means of varying the torque is to establish a prescribed torque in the operating spindle. If a load that exceeds the established torque is applied to the operating spindle, through a bit that communicates with it for example, the torque-disengagement mechanism will disengage the motor. A known machine of this type is disengged by means of a clutch. This prevents excessive driving for example if the electric tool is acting as a screwdriver, and decreases the jolt or opposing force upon termination of the driving action.
The necessity of interposing a torque clutch between the transmission and main shaft, which makes the machine, especially a portable electric tool, a lot longer, is considered a drawback.
Mounting wire strain gauges on at least one of the driveshafts to measure the rotation of the shaft occasioned by the opposing torque has been proposed. Strain gauges are, however, appropriate for testing purposes and not for use in mass-produced articles.